Conventionally, there is known a semiconductor apparatus having wiring substrates layered on top of each other by way of connection terminals (e.g., solder balls) and including one or more electronic components (e.g., semiconductor chips) mounted on the wiring substrates. For example, the semiconductor apparatus may be obtained by manufacturing multiple wiring substrates that include a semiconductor chip flip-chip bonded to a front surface of the wiring substrate and an electrode pad provided on the front and back surfaces of the wiring substrate, and using solder balls to bond the electrode pads provided on vertically adjacent wiring substrates (see, for example, Japanese Laid-Open Patent Publication No. 11-8474).
However, because the above-described semiconductor apparatus uses connection terminals such as solder balls having substantially spherical shapes, a mismatch of impedance occurs at apart of the connection terminals in a case of attempting to transmit high frequency signals between the vertically adjacent wiring substrates by way of the connection terminals. Therefore, it is difficult for the semiconductor apparatus to transmit high frequency signals by way of connection terminals.